Endothelial Progenitor Cells inhibit jaw osteonecrosis in a rat model: A major adverse effect of bisphosphonate therapy

Abstract

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse effect of antiresorptive and antiangiogenic therapies. MRONJ is identified by chronic wounds in the oral mucosa associated with exposed necrotic bone. We hypothesized that zoledronic acid (ZOL) impairs keratinocyte and fibroblast function and reduces soft tissue vascularization; therefore, treating MRONJ with proangiogenic cells may benefit MRONJ patients. The effect of ZOL and dexamethasone (DEX) on gingival fibroblasts and keratinocytes was investigated. In-vitro, ZOL inhibited fibroblast and keratinocyte proliferation, delaying scratch healing. In-vivo, exposed bone was detected at tooth extraction sites, mainly in ZOL(+)/DEX(+) rats; and was associated with significantly decreased soft tissue vascularization, serum-VEGF, and tissue-VEGF. Local injection of early and late endothelial progenitor cells (EPCs) healed 13 of 14 MRONJ lesions compared with 2/7 lesions in the mesenchymal stem cells, and 2/6, in culture-medium group. The EPCs reduced necrotic bone area, increased serum and tissue VEGF levels. EPCs engraftment was minimal, suggesting their paracrine role in MRONJ healing. The EPC-conditioned medium improved scratch healing of keratinocytes and fibroblasts via VEGF pathway and elevated mRNA of VEGFA and collagen1A1. In conclusion, a novel MRONJ treatment with EPCs, increased vascularization and improved epithelial and fibroblast functions as well as cured the lesion.

Endothelial progenitors increase vascularization and improve fibroblasts function that prevent medication‐related osteonecrosis of the jaw

“…However, ZOL + DEX rats that developed MRONJ-like lesions showed epithelium discontinuation with fragments of non-vital bone surrounded by non-specific inflammatory infiltrate. Serum VEGF was higher in the saline group compared to ZOL + DEX group (p = .009), and the volume of blood vessels was lower in the ZOL + DEX compared to the saline group (p = .007) (Tamari et al, 2019). Overall, these results led us to conclude that MRONJ pathogenesis involves reduced vascularity.…”

“…Moreover, blocking VEGF pathway in the same cells decreased their recovery after ZOL/ DEX treatment in response to EPC-CM. (Tamari et al, 2019).…”

“…Cells were cultured with DMEM (control), or DMEM supplemented with 10 µM ZOL, 10 µM DEX, or 10 µM ZOL + DEX. Drug concentration was based on our previous study in which a dose-response effect (0-100 μM) was performed (Tamari et al, 2019). Cells were incubated for a total of 72 hr.…”

“…Before sacrifice, 3 ml Dil solution (Thermo Fischer) was perfused into the internal carotid artery as described earlier (Tamari et al 2019). Then, animals were sacrificed, and a sample of the oral mucosa was excised from the extraction healing site and embedded in 1% agarose gel.…”

“…All animals received bilateral local injection in the area of the first molar with either 5 × 10 5 human EPCs (in 150 µl EGM-2) (n = 10) or EGM-2 (n = 10). Cell concentration was used based on our previous studies in which hEPCs were locally injected to treat MRONJ(Tamari et al, 2019) or to enhance bone regeneration(Zigdon-Giladi et al, 2015).At 3 weeks, rats were anaesthetized as described previously and the first right and left molars were extracted. Postoperative and 3 days postextraction, rats were treated with 0.3 mg/kg bw Buprenorphine (Vetamarket) and 50 mg/kg bw Cephalexin (Norbrook Laboratories) that were injected s.c.…”